Social Bookmarking sites, PR and Dofollow

We have already dealt with

Social Bookmarks

here and many other times we talked about the importance that they have in the phase of

backlinks increasing

. Casually, I came upon this long list of sites (all Social Bookmark), in which is specified in the PR and if they are DoFollow or No Follow of each one: LIST

DirectoryRoll is sharing this social bookmarking list with webmasters and social media enthusiasts. We have 394 social bookmarking/networking sites in our list.
www.directoryroll.com

Obviously it is difficult to post an article on all these sites, and in a short time, but a bit 'a day you can always try.
See also, Social Bookmark Submitter, software reviews - social bookmarking tools